Stefano Stabellini 340720be32 xen/arm: reimplement xen_dma_unmap_page & friends ... xen_dma_unmap_page, xen_dma_sync_single_for_cpu and xen_dma_sync_single_for_device are currently implemented by calling into the corresponding generic ARM implementation of these functions. In order to do this, firstly the dma_addr_t handle, that on Xen is a machine address, needs to be translated into a physical address. The operation is expensive and inaccurate, given that a single machine address can correspond to multiple physical addresses in one domain, because the same page can be granted multiple times by the frontend. To avoid this problem, we introduce a Xen specific implementation of xen_dma_unmap_page, xen_dma_sync_single_for_cpu and xen_dma_sync_single_for_device, that can operate on machine addresses directly. The new implementation relies on the fact that the hypervisor creates a second p2m mapping of any grant pages at physical address == machine address of the page for dom0. Therefore we can access memory at physical address == dma_addr_r handle and perform the cache flushing there. Some cache maintenance operations require a virtual address. Instead of using ioremap_cache, that is not safe in interrupt context, we allocate a per-cpu PAGE_KERNEL scratch page and we manually update the pte for it. arm64 doesn't need cache maintenance operations on unmap for now. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Tested-by: Denis Schneider <v1ne2go@gmail.com>		2014-09-11 18:11:53 +00:00
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asm	xen/arm: reimplement xen_dma_unmap_page & friends	2014-09-11 18:11:53 +00:00
debug	ARM: SoC platform changes for 3.17	2014-08-08 11:14:29 -07:00
uapi/asm	ARM: wire up memfd_create syscall	2014-08-09 14:07:59 +01:00